Copolymer of a monovinyl ether of a glycol and nu-vinyl-2-oxazolidinone and rubber made by vulcanizing same



3,092,605 (IQPOLYMER OF A MONO ETI ER 6F A GLYCOL AND N VINYL 2 OXAZOLIDINONE AND RUBBER MADE BY VULCANIZWG SAME George B. Sterling and Robert L. Zimmerman, both of Midland, Mich, assignors to The Dow Chemical Company, Midland, Mich a corporation of Delaware No Drawing. Filed May 8, 1961, Ser. No. %,288 13 Claims. (Cl. 260-41) This invention relates to compositions of matter comprising rubbery copolymers and vulcanizates thereof. More particularly, this invention is concerned with copolymers of monovinyl ethers of glycols with certain N- vinyl-Z-oxazolidinones and to vulcanized compositions made from such copolymers.

It is known that rubbery copolymers can be made by the copolymerization of various monomers such as styrene with butadiene, acrylonitrile with butadiene, and isobutylene with butene. As the search continues for monomers and combinations of monomers which will produce rubbery material when subjected to polymerization, it has been found that many monomers produce inflexible resinous products and that elastorneric materials are difficult to produce. In addition, known rubbery polymers contain residual unsaturation to which is attributed their susceptibility to oxidative attack.

It is among the objects of the present invention to provide a new rubbery composition of matter. A further object of the present invention is the provision of a vulcanized product suitable for use in place of vulcanized natural rubber. Another object of the present invention is the provision of a novel reinforced elastomeric composition. A further object of the present invention is to produce elastomeric compositions which are free of residual unsaturation. These and other objects are attained in accordance with the practice of the present invention as will appear from the following description.

It has now been discovered, and the discovery forms the basis 'of the invention, that elastomeric compositions can be produced by reacting the monovinyl ether of a glycol with certain N-vinyl-Z-oxazolidinones. The resulting rubbery copolymers can be compounded with reinforcing agents and cured to produce vulcanized rubbers of superior quality.

The monovinyl ethers suitable for the production of copolymers and vulcanizates of the present invention are the monovinyl ethers of glycols and are represented by the general formula HO--(C H O) Cl-i CI-I in which n is a positive integer from 2 to 4 and in which 2: is a positive integer from 1 to 3. Representative examples of such compounds are the conovinyl ether of ethylene glycol, the monovinyl ether of trimethylene glycol, the monovinyl ether of propylene glycol, the monovinyl others of the butylene glycols, the monovinyl ether of diethylene glycol, the monovinyl ether of tripropylene glycol and the monovinyl ether of dibutylene glycol.

The monomers copolymerizable with the monovinyl others to prepare the elastomers of the present invention are certain N-viny1-2-oxazolidinones including N-vinyl-Z- oxazolidinone and ring substituted lower alkyl derivatives thereof in which the alkyl group contains from 1 to about 4 carbon atoms. The ring substituted derivatives can have from 1 to 4 such lower alkyl substituents. Representative examples of ring substituted lower alkyl derivatives of N vinyl-2-oxazolidinone are N-vinyl-4-methyl-2-oxazolidinone, N-vinyl-4-ethyl-2-oxazolidinone, N-vinyl-4-propyl-2-oxazolidinone, N-vinyl-S-methyl-Z-oxazolidinone, N-vinyl-S-ethyl-Z-oxazolidinone,

N-vinyl-S-isobutyl-Z-oxazolidinone, N-vinyl-4,S-dimethyl-2-oxazolidinone, N-vinyl-4,4,5,5-tetramethyl-2-oxaz0lidin0ne, N-vinyl-4,5-diethyl-2-oxazolidinone, and N- vinyl-4-methyl-S-ethyl-Z-oxazolidinone.

The new copolymers can be produced by emulsion, mass or solution polymerization or by any of the other usual polymerization techniques. Advantageously the copolymers of the present invention are produced by reacting the comonomeric materials in a confined zone in the presence of suitable catalysts such as free radical catalysts. The materials are preferably agitated slowly and maintained at elevated temperatures during the polymerization reaction.

It is found that rubbery polymers can be produced which contain in polymerized form between about 50 percent and about 90 percent by weight of the monovinyl ether and between about 10 percent and about 50 percent by weight of l l-vinyl-Z-oxazolidinone and the alkyl derivatives hereinabove referred to. Good elastomeric materials are provided by polymers containing in the polymer molecule between about 60 percent and about percent by weight of the monovinyl ether and between about 20 percent and about 40 percent by weight of the oxazolidinone compounds.

The copolymers of the present invention can be vulcanized by compounding the copolymers with vulcanizing agents and subjecting the compounded materials to curing conditions. For example, the crude rubbery material can be compounded with vulcanizing agents such as sulfur, sulfur chloride and aniline butyroaldehyde. When the crude rubbery material is to be converted into vulcanized products, it is highly desirable that the crude material be compounded with a reinforcing filler since it is found that such fillers substantially increase the tensile strength and improve other physical properties of the vulcanizate. Representative examples of reinforcing fillers are the various carbon blacks including lamp black, channel black, furnace black and the like, zinc oxide and kaolin. It is desirable to include an accelerator in the compounding in order to reduce the amount of time necessary to carry out the vulcanization. Representative examples of accelerators suitable for use in producing the vulcanizates of the present invention are benzothiazolyl disulfide, 2- mercaptobenzothiazole, 1,3-diphenylguanidine, and zinc dimethyldithiocarbamate. Advantageously, the crude rubber is also compounded with an activator to initiate the vulcanization reaction. Among the activators suitable for use with the herein described copolymers to produce the vulcanized products of the present invention are stearic acid, zinc oxide, lead oxide and magnesium oxide.

The compounding of the crude rubber can be done by malaxing, kneading, milling or otherwise intimately blending the crude rubber of this invention with the compound ing ingredients in the desired proportions as by compounding the materials with one another in an internal mixed such as a plastics extruder or a Banbury mixer or on an external mixer such as an open-faced roll mill to form a homogeneous composition.

The following example is illustrative of the present invention but the invention is not limited to the specific details thereof. All parts and percentages are parts and percentages by weight unless otherwise specified.

Example There are placed in a 12-ounce citrate bottle 80 grams of the monovinyl ether of diethylene glycol, 20 grams of N-vinyl-5-methyl-2-oxazolidinone, 5 grams of lauroyl peroxide and 5 grams of u,u-azobis(isobutyronitrile), the latter two materials acting as polymerization catalysts. The bottle is then flushed with nitrogen, capped and clamped'into a tumbler-type washing machine. The machine is operated at 40 rotations per minute and kept at a temperature of 60 C. for 30 hours. The bottle is removed from the machine and broken to obtain the contents which is a gel of polymer and monomer. The polymer is devolatized by heating for hours at a temperature of 100 C. and at an absolute pressure of 10 mm. of mercury. There is obtained 50.3 grams of crude rubbery copolymer containing in polymerized form 28.6 percent of N-viny-l-5-methyl-2-oxazolidinone and 71.4 percent of the monovinyl ether of diethylene glycol.

Forty parts of the crude rubbery copolymer is fed onto a cold two-troll mill. There are then compounded with the polymer on the mill for minutes 16 parts of furnace black, 2 parts of zinc oxide, 8 parts of sulfur and 1.2 parts of benzothiazolyl disulr'ide, an accelerator. The homogeneous mixture is then placed in a mold and cured at a temperature of 145 C. for 50 minutes under a pressure of 1 000 p.s.i. The cured product when tested in the manner described in A.S.T.M. D4l25 1T exhibits an elongation of 100 percent, a tensile strength of 695 pounds per square inch, and a permanent set of zero. When tested in accordance with A.S.T.M. D67655T the material is found to possess a Shore A hardness of 57 and a Shore C hardness of 23. In a manner similar to the foregoing example each of the monovinyl others within the class above defined and 4 which the comonomer is N-vinyl-S-methyl-Z oxazolidinone.

4. A composition of matter according to claim 3 in which the monovinyl ether is the monovinyl ether of diethylene glycol.

5. A composition of matter cornprisin a copolymer containing in polymerized form from about 60 percent to about 80 percent by weight of a monovinyl ether represented by the general formula lO(C H O) CH=CH in which n is a positive integer h'om 2 to 4 and in which x is a positive integer from 1 to 3, and from about 20 perto about percent by weight of a comonomer selected mixtures thereof are copolymerizable with each of the N-vinyl-Z-oxazolidinones within the class above defined and mixtures thereof to produce rubbery copolyrners which can be compounded with reinforcing fillers and cured to produce vulcanizates having pro erties similar to those obtained above.

The new compositions possess good processability and can be compounded in accordance with standard formulations and according to standard techniques. The compounding can include materials in addition to those given above, such as peptizers, plasticizers, softeners, retarders, antioxidants, extenders, and coloring materials as well as various factices, natural, synthetic and reclaimed rubbers. The compositions are useful for making a variety of rubber articles including sheets, films, gaskets, electrical insulation and the like, by well known techniques such as molding, calendering, extruding and the like.

As will be appreciated, various modifications can be made within the scope of the present invention without departing from the spirit thereof.

That which is claimed is:

1. A composition of matter comprising a copolymer containing in polymerized form between 50 percent and about 90 percent by weight of a monovinyl ether represented by the general formula in which n is a positive integer from 2 to 4 and in which x is a positive integer from 1 to 3, and between about 10 percent and 50 percent by weight of a comon-omer selected from the group consisting of N-vinyl-Z-oxazolidinone and ring substituted alkyl derivatives thereof in which the alkyl group contains from '1 to about 4 carbon atoms.

2. A composition of matter according to claim 1 in which the monovinyl ether is the monovinyl ether of diethylene glycol.

3. A composition of matter according to claim 1 in from the group consisting of N-vinyl-2-oxazolidinone and ring substituted alkyl derivatives thereof in which the alkyl group contains from 1 to about 4 carbon atoms.

6. A composition of matter according to claim 5 in which the monovinyl ether is the monovinyl ether of diethyiene glycol.

'7. A composition of matter according to claim 5 in which the comonomer is N-vinyl-S-methyl-Z-oxazolidiru one.

8. A composition of matter according to claim 7 in which the monovinyl ether is the monovinyl ether of diethylene glycol.

9. A synthetic rubber made by vulcanizing a composition of matter to cross link the same, said composition of matter comprising a ccpolymer of a monovinyl ether represented by the general formula HO- (C H CH CH in which n is a positive integer from 2 to 4 and in which x is a positive integer from 1 to 3, and a conic-homer selected from the group consisting of N-vinyl-Z-oxazo'lidinone and ring substituted alkyl derivatives thereof in which the alkyl group contains from 1 to about 4 carbon atoms, there being present in the copolymer in polymerized form between 50 percent and about 90 percent by weight of the monovinyl ether and between about 10 percent and 50 percent by weight of the comonomer and a reinforcing filler.

10. A synthetic rubber according to claim 9 in which the monovinyl ether is the monovinyl ether of diethylene glycol.

11. A synthetic rubber according to claim 9 in which the coinonomer is N-vinyl-5-rnethyl-2-oxazolidinone.

12. A synthetic rubber according to claim 9 in which the reinforcing filler is carbon black.

13. A synthetic rubber made by vulcanizing a'composition of matter to cross link the same, said composition of matter comprising a copolymer of the monovinyl ether of diethylene glycol and N-vinyl-5-rnethyl-2-oxazolidino-ne, there being present in the copolymer in polymerized form about percent to about percent by weight of the monovinyl ether and about 20 percent to about 40 percent by weight of N- vinyl-5-methyl-2-oxazolidinone and carbon black.

References (iited in the file of this patent UNITED STATES PATENTS 

1. A COMPOSITION OF MATTER COMPRISING A COPOLYMER CONTAINING IN POLYMERIZED FORM BETWEEN 50 PERCENT AND ABOUT 90 PERCENT BY WEIGHT OF A MONOVINYL ETHER REPRESENTED BY THE GENERAL FORMULA 